1. Field of the Invention
The present invention relates to a method of percutaneously removing a thrombus from an artery or a vein in various parts of the body by using catheters, and a system for removing a thrombus from a blood vessel by using catheters. More particularly, the invention relates to a method and a system for percutaneously removing a thrombus from a blood vessel by using catheters, which method and system are well suited for removing a thrombus from a coronary artery in particular.
2. Description of the Prior Art
There are various causes for acute myocardial infarction, and one of the known causes is blocking of a coronary artery by a thrombus. Techniques employed heretofore to treat this type of blocking by a thrombus are classified broadly into the following three methods:
(a) A surgical, bypassing operation for the location of thrombosis,
(b) Percutaneous Transluminal Coronary Recanalization (known as PTCR), and
(c) Percutaneous Transluminal Coronary Angioplasty (known as PTCA).
The surgical operation above is a major operation involving chest incision and running considerable risks. It resorts to bypassing and not removal of the thrombus per se. Such an operation is seldom carried out since it is costly.
PTCR is a method in which a thrombus dissolving agent is injected to the location of thrombosis in a coronary artery by using catheters. This method has the following problems:
1. Although PTCR may succeed in resuming blood flow, the thrombus is not completely dissolved. Consequently, stenotic lesion remains in a serious degree, which may cause post-infarction angina pectoris and re-blocking.
2. Where a large quantity of thrombus dissolving agent is used in order to completely dissolve and remove the thrombus, the dissolving agent is injected from a catheter to a position adjacent the location of thrombosis and becomes diluted by blood before the dissolving agent reaches the location of thrombosis. If the quantity of thrombus dissolving agent is increased to anticipate the dilution, not only hemorrhage will occur at other locations than the heart but there are many cases of hemorrhage occurring at the location of myocardial infarction with blood flow resumption, namely hemorrhagic infarction.
PTCA is a method of pressurizing and expanding a location of coronary artery blockage from inside by inflating a balloon attached to a catheter.
Since, in the state of the art, PTCA leaves the thrombus as it is instead of removing it, there is a problem of re-blocking taking place immediately following or several months after the treatment. This method has a further problem that the thrombus broken up through pressurization and expansion of the thrombotic location may block peripheral blood vessels, thereby causing a circulatory disorder.